1. Field of the Invention
The present invention relates to a method of recovering lithium from batteries by separating lithium contained in the lithium-containing member such as an cathodic active material of a lithium ion secondary battery which is used as a power source for various electronics such as VTRs and communication tools.
2. Related Art
Nonaqueous electrolytic batteries attract considerable attention as the battery with a high energy density and have come to be widely used as the power source for electronics along with the recent progress of a variety of down-sized and light-weight electronics such as VTRs, communication tools and the like. Among these nonaqueous electrolytic batteries, lithium ion secondary batteries, unlike other secondary batteries, do not contain the metal components of which use must be carefully considered from the standpoint of environmental problems, such as mercury, cadmium and lead, and are also characterized by having a sufficient cycle life. Hence the usage of the lithium ion secondary batteries is steadily increasing.
As for materials used for the lithium ion secondary batteries, both of materials currently used and materials proposed for the next generation contain rare metals such as cobalt and the like, which are specified as the national stock material. Hence public attention is focused on the recovery of rare metals from used lithium ion secondary batteries to reuse these metals.
As the process for separation and recovery of lithium from cathodic active materials of the lithium ion secondary batteries, there is a conventional process in which the batteries are calcined and crushed, the crushed batteries are dissolved in an acid after iron is removed from the crushed batteries by means of magnetic separation, the pH of the solution is adjusted and then sodium carbonate is added to the solution to precipitate the lithium element as lithium carbonate, thereby separating and recovering the lithium element from the solution. This process for the recovery of lithium can yield a recovery product of lithium of relatively high purity.
This process, however, can be applied only to the batteries using a specific lithium oxide as the cathodic active material and only exhibits a low recovery yield.
Another recovery processes include steps of separating only cathodic materials from the batteries, removing substrate aluminum from the anodic materials, and subsequently crushing the remaining cathodic active material for reuse. In this case, however, the cathodic active material contains many other components and the composition of the cathodic active material has changed by use. Therefore, the removal of impurities and the adjustment of the components are necessary, resulting in the problem of raising the total cost.